The present invention relates to an air bag system which can effectively restrain an occupant, and more particularly to a gas generator including two or more combustion chambers, two igniters, two different gas generating means, an igniter having a lead wire, a combustion chamber, ignition means provided in an inner cylindrical member, and an automatic ignition material.
An air bag system, which is mounted on various kinds of vehicles and the like including automobiles, aims to hold an occupant of the vehicle by means of an air bag (a bag body) . The air bag is rapidly inflated by a gas when the vehicle collides at a high speed so as to prevent the occupant from crashing into a hard object inside the vehicle, such as a steering wheel and windscreen, due to an inertia and from being injured. This kind of air bag system generally comprises a gas generator actuated according to a collision of the vehicle and discharge a gas, in order to introduce the gas into the air bag to inflate the air bag.
It is desired that the air bag system of this type can safely restrain the occupant even when frame of the occupant (for example, whether a sitting height of the occupant is long or short, whether the occupant is an adult or a child, and the like), a sitting attitude (for example, an attitude of the occupant holding the steering wheel) and the like are different. Then, there has been conventionally suggested an air bag system which actuates by applying as small as possible impact to the occupant at the initial stage of the actuation. Gas generators in such a system are disclosed in JP-A 8-207696, U.S. Pat. Nos. 4,998,751, and 4,950,458. JP-A 8-207696 suggests a gas generator, in which one igniter ignites two kinds of gas generating agent capsules so as to generate the gas in two stages. U.S. Pat. Nos. 4,998,751 and 4,950,458 suggest a gas generator, in which two combustion chambers are provided for controlling actuation of the gas generator so as to generate the gas in two stages due to an expanded flame of the gas generating agent.
However, these gas generators have drawbacks in that an internal structure thereof is complicated, a size of a container is large, and a cost therefor becomes expensive.
Further, in JP-A 9-183359 and DE-B 19620758, there is disclosed a gas generator, in which two combustion chambers, each storing a gas generating agent, are provided in a housing and an igniter is arranged in each combustion chamber, so as to adjust an activation timing of each of the igniters, thereby adjusting an output of the gas generator. However, in the above gas generators, since the igniters arranged in the respective combustion chambers are independently arranged, it becomes difficult to assemble (manufacture), the structure itself of the gas generator becomes complicated and a volume thereof becomes large.
In order to solve the above-problems, the present invention provides a gas generator which actuates while applying as small an impact as possible to an occupant at the initial stage of an operation and can widely and selectively adjust an output and timing of an output increase of the gas generator so as to safely restrain the occupant even when frame of the occupant (for example, whether a sitting height of the occupant is long or short, whether the occupant is an adult or a child, and the like), a sitting attitude (for example, an attitude of the occupant holding the steering wheel) and the like are different, as well as restricting the total size of a container, providing a simple structure and that can be easily manufactured.
A gas generator for an air bag according to the present invention corresponds to a gas generator, in which two combustion chambers are provided in a housing, and is characterized by a structure of arranging two combustion chambers. In particular, it is also possible to independently ignite and burn gas generating means accommodated in each combustion chamber by a different ignition means.
Namely, according to the present invention, there is provided a gas generator for an air bag, which includes, in the housing having a gas discharge port or gas discharge ports, ignition means activated upon an impact, and gas generating means ignited and burnt by the ignition means and generate a combustion gas for inflating an air bag, wherein, in the housing, two combustion chambers for storing the gas generating means are concentrically provided so as to be adjacent to each other in the radial direction of the housing, and a communicating hole to allow communication between the combustion chambers is provided.
Further, according to the present invention, there is provided a gas generator for an air bag, which includes ignition means activated upon an impact, and gas generating means ignited and burnt by the ignition means and generate a combustion gas for inflating an air bag in a housing formed in a cylindrical shape having an axial core length longer than an outermost diameter, having a plurality of gas discharge ports on a peripheral wall thereof, wherein, in the housing, two combustion chambers for storing the gas generating means are concentrically provided so as to be adjacent to each other in the axial direction and/or the radial direction of the housing, and a communicating hole to allow communication between the combustion chambers is provided.
It is possible to provide two combustion chambers concentrically to be adjacent to each other in the axial direction and/or the radial direction of the housing. The two combustion chambers are formed in a cylindrical shape and an annular shape.
As mentioned above, by forming two combustion chambers in the housing, it is possible to make an inner structure of the gas generator simple and independently burn the gas generating agents in the respective combustion chambers.
The gas generating means mentioned above is provided to inflate the air bag for restraining the occupant by the combustion gas generated by the combustion thereof. Accordingly, when the ignition means includes a transfer charge which is ignited and burnt by the igniter to burn the gas generating means, the combustion gas generated by the combustion of the transfer charge is used for burning the gas generating means and is not directly used for inflating the air bag. In this respect, both can be definitely distinguished from each other. Further, two combustion chambers provided in the housing is exclusively used for storing the gas generating means. In this respect, even when the ignition means is composed to include the transfer charge and the transfer charge is installed in a defined space (hereinafter, refer to as xe2x80x9can accommodating chamberxe2x80x9d), this accommodating chamber of the transfer charge and the combustion chamber storing the gas generating means can be definitely distinguished from each other.
When the ignition means for igniting and burning the gas generating means includes two or more igniters to be actuated upon an impact, it is preferable that, in order to make the mounting thereof easy, the igniters are provided in a single initiator collar aligned to each other in the axial direction. Further, when the ignition means also includes the transfer charge which is ignited and burned in response to an activation of the igniters, it is preferable that the transfer charge is partitioned for each igniter, and independently ignited and burned by each igniter, and therefore is formed such that a flame of the transfer charge for one of the igniters does not directly ignite the transfer charge in any other igniters. As this type of structure, for example, it is possible to arrange the igniters in the respectively independent igniter accommodating chambers and then arrange the transfer charges in the igniter accommodating chambers, or to arrange the transfer charges in a place inside the independent combustion chambers where the transfer charges can be ignited and burnt in response to the activation of the igniter.
As mentioned above, in the case of dividing the transfer charge for each igniter, the gas generating means stored in two combustion chambers are ignited and burnt by the flame generated by burning the transfer charges arranged separately in the respective sections. That is, since the transfer charge in each section burns in response to the activation timing of the igniter, and the gas generating means in each combustion chamber can separately burn, an actuation performance of the gas generator can be optionally controlled.
Therefore, by adopting the structure of the gas generator according to the present invention, the transfer charge partitioned for each igniter can be independently burnt by changing the respective ignition timing of each igniter and accordingly, the ignition and combustion timing of the gas generating means in each combustion chamber can be staggered, therefore, the output of the gas generator can be optionally adjusted.
With respect to the two combustion chambers provided in the housing, either of the combustion chambers may be provided in the axial direction of the igniter and the other combustion chamber may be provided in the radial direction of the ignition means. Further, in the case of characteristically adjusting the actuation performance of the gas generator, particularly a change with the passage of time in the gas discharge amount, the two combustion chambers are charged with the gas generating means which are different in at least one of a burning rate, composition, composition ratio, and an amount from each other, respectively, and the respective gas generating means can be independently ignited and burnt at an optional timing. Further, at each combustion chamber, the gas generating means having a different gas amount generated at a unit time may be stored.
As the gas generating means, in addition to an azide gas generating agent based on inorganic azide which has been widely used, for example, sodium azide, non-azide gas generating agent not based on inorganic azide may be used. However, from the view of safety, non-azide gas generating agent is preferable, and as the non-azide gas generating composition, for example, a composition containing nitrogen containing organic compound such as tetrazole, triazole or metallic salt thereof and an oxygen containing oxidant such as alkali metal nitrate, a composition using triaminoguanidine nitrate, carbohydroazide, nitroguanidine, and the like as fuel and nitrogen source and using nitrate, chlorate, perchlorate or the like of an alkali metal or an alkaline earth metal as an oxidant, and the like may be employed. In addition, the gas generating means can be suitably selected according to requirements such as a burning rate, non-toxicity, combustion temperature, and decomposition starting temperature. In the case of using the gas generating means having different burning rates in the respective combustion chambers, the gas generating means having the different composition or composition ratio itself may be used, such that, for example, the inorganic azide such as the sodium azide or the non-azide such as the nitroguanidine is used as the fuel and the nitrogen source. Alternatively, the gas generating means obtained by changing the shape of the composition to a pellet shape, wafer shape, hollow cylindrical shape, disc shape, single hole body shape or a porous body shape, or the gas generating means obtained by changing a surface area according to the size of a formed body may be used. In particular, when the gas generating means is formed into the porous body with a plurality of through holes, an arrangement of the holes is not particularly limited, however, in order to stabilize the performance of the gas generator, an arrangement structure such a distance between an outer end portion of the formed body and the center of the hole and a distance between each center of the holes are substantially equal to each other is preferable. Concretely, in the cylindrical body having a circular cross section, for example, a preferred structure is such that one hole is arranged at the center and six holes are formed around the hole so that the center of each hole is the apex of regular triangles of the equal distances between the holes. Further, in the same manner, an arrangement such that eighteen holes are formed around one hole at the center may be also suggested. However, the number of the holes and the arrangement structure are determined in connection with easiness of manufacturing the gas generating agent, manufacture cost, and performance, and are not particularly limited.
Among the two combustion chambers mentioned above, the combustion chamber provided outside in the radial direction may contain coolant means for cooling the combustion gas generated due to combustion of the gas generating means on the side of a peripheral wall of the housing thereof. The coolant means is provided in the housing for the purpose of cooling and/or purifying the combustion gas generated due to the combustion of the gas generating means. For example, in addition to a filter for purifying the combustion gas and/or a coolant for cooling the generated combustion gas which have been conventionally used, a layered wire mesh filter obtained by forming a wire mesh made of a suitable material into an annular layered body and compress-molding, and the like can be used. The layered wire mesh coolant can be preferably obtained by forming a plain stitch stainless steel wire mesh in a cylindrical body, folding one end portion of the cylindrical body repeatedly and outwardly so as to form an annular layered body and then compress-molding the layered body in a die, or by forming a plain stitch stainless steel wire mesh in a cylindrical body, pressing the cylindrical body in the radial direction so as to form a plate body, rolling the plate body in a cylindrical shape at many times so as to form the layered body and then compress-molding it in the die. Further, the coolant with a double structure with different layered wire mesh bodies at an inner side and an outer side thereof, which has a function for protecting the coolant means in the inner side and a function for suppressing expansion of the coolant means in the outer side, may be used. In this case, it is possible to restrict expansion by supporting an outer periphery of the coolant means with an outer layer such as the layered wire mesh body, the porous cylindrical body, the annular belt body.
In the case of the gas generator, in which combustion gas generated due to combustion of the gas generating means stored in two combustion chamber reaches the gas discharge port via a different flow paths in each combustion chamber so that the gas generating means stored in one combustion chamber is not directly ignited due to the combustion gas generated in the other combustion chambers, the gas generating means in the combustion chambers burns in each chamber in a completely independent manner, and therefore, the gas generating means in each combustion chamber is ignited and burnt in more secure manner. As a result, even when activation timings of two igniters are staggered significantly, the flame of the gas generating means in the first combustion chamber, ignited by the firstly actuated igniter, does not burn the gas generating means in the other combustion chambers, so that a stable output can be obtained. This kind of gas generator can be achieved, for example, by arranging a flow passage forming member in the housing so as to form the flow passage and introducing the combustion gas generated in the first combustion chamber to the coolant means directly.
The housing, mentioned above, can be obtained by forming a diffuser shell, having a gas discharge port or gas discharge ports, and a closure shell, which forms a storing space together with the diffuser shell, by casting, forging, press-molding or the like, and joining both shells. The joining of both shells can be performed by various kinds of welding methods, for example, electron beam welding, laser welding, TIG arc welding, projection welding, or the like. Forming the diffuser shell and the closure shell by press-molding various kinds of steel plates, such as stainless steel plate, makes manufacture easy and reduces manufacturing cost. Further, forming both shells into a simple shape, such as a cylindrical shape, makes the press-molding of the shells easy. With respect to the material of the diffuser shell and the closure shell, stainless steel is preferable, and the material obtained by applying nickel plating to the steel plate may be also acceptable.
In the housing mentioned above, the ignition means actuated upon detection of an impact and ignites and burns the gas generating means is further installed. In the gas generator according to present invention, as the ignition means, electric ignition type ignition means activated by an electric signal (or an activating signal) transmitted from an impact sensor or the like which detects the impact is used. The electric ignition type ignition means comprises an igniter activated by the electric signal transmitted from the electric sensor which exclusively detects the impact by means of an electric mechanism, such as a semiconductor type acceleration sensor or the like, and a transfer charge ignited and burnt by the activation of the igniter as required.
The gas generator for the air bag mentioned above is accommodated in a module case together with an air bag (bag body) to introduce the gas generated in the gas generator and inflate, so as to form the air bag apparatus. In this air bag apparatus, the gas generator is actuated when an impact is detected by the impact sensor, and the combustion gas is discharged from the gas discharge port in the housing. The combustion gas flows into the air bag, whereby the air bag breaks the module cover to inflate, and forms a cushion for absorbing the impact between a hard member in the vehicle and an occupant.
The other aspects of the present invention will be described below. The parts and combination mentioned above can be utilized in the respective aspects. Only features of the respective aspects will be described below.
Next, a description will be given below of a gas generator including two or more combustion chambers.
There is provided a gas generator for an air bag which can burn the gas generating means in each combustion chamber at a different timing and/or power, in addition to igniting and burning the gas generating means stored in each combustion chamber at a different timing.
Namely, according to the present invention, a gas generator for an air bag which installs, within a housing, gas discharge port, ignition means activated upon an impact, and gas generating means ignited and burnt by the ignition means and generate combustion gas for inflating an air bag, is characterized in that in the housing, two or more combustion chambers for storing the gas generating means are defined, the gas generating means stored in each combustion chamber is independently ignited and burnt by the ignition means provided at each combustion chamber, and the gas generating mean stored in each combustion chamber is different from the ones in the other chambers in at least one of a burning rate, shape, composition, composition ratio, and amount.
The combustion chambers provided in the housing, for example, in the case of two chambers, can be arranged such that they are concentrically provided so as to be adjacent to each other in the radial direction of the housing and a communication hole, which allows communication between the combustion chambers, is provided.
As mentioned above, the gas generating means, which is different from the ones in the other chambers in at least one of the burning rate, shape, composition, composition ratio, and amount, are stored in a plurality of combustion chambers defined in the housing, and therefore the actuation performance of the gas generator, in particular, the change in the volume of the discharged gas with the passage of time can be characteristically adjusted by independently igniting and burning the gas generating means at an optional timing. The combustion chambers are charged by the gas generating means to provide different gas amounts generated at a unit time from each other, respectively. That is, in the case of the gas generator for the air bag using the same kind of gas generating means for the respective combustion chambers, the actuation performance thereof is definitely determined according to the actuation timing of the ignition means provided in each combustion chamber. However, when the combustion chambers are charged with the gas generating means to provide the different combustion characteristics (for example, the burning rate, shape, composition, composition ratio, and amount) from each other, respectively, according to the present invention, the operation performance of the gas generator can be adjusted freely even though the actuation timings of the ignition means are the same. Accordingly, when adjusting the actuation timing of the igniter as well as the gas generating means stored in each combustion chamber, it is possible to adjust widely and finely the operation performance of the gas generator. In particular, in the case of changing the shape of the gas generating means in each combustion chamber, the shape can be varied by changing a thickness or surface area of the gas generating agent, and in the case of changing the amount of the gas generating means in each combustion chamber, the weight of the gas generating means stored in each chamber can be different from the others.
In the gas generator mentioned above, in the case that a plurality of combustion chambers are defined in the housing and charged with the gas generating means to provide different burning rates from each other in the respective combustion chambers, with respect to a burning rate (Vs) of the gas generating means with a small burning rate stored in any combustion chamber, a value (Vl/Vs) of a burning rate (Vl) of the gas generating means with a large burning rate stored in another combustion chamber can be adjusted to a range of between larger than 1 and smaller than 14. For example, in the case of partitioning the housing into two chambers (that is, first and second combustion chambers) and respectively arranging a first gas generating means and a second gas generating means in the first combustion chamber and the second combustion chamber, it is possible to adjust a burning rate of the first gas generating means to a burning rate of the second gas generating means (mm/sec) in a range of between 3:40 and 40:3.
Further, when a plurality of combustion chambers are charged with the gas generating means having different shapes from each other, respectively, the gas generating means stored in one combustion chamber and the gas generating means stored in another combustion chamber can be different from each other in thickness and/or surface area thereof. For example, if the gas generating means having a different thickness for each combustion chamber are used, with respect to a thickness (Ts) of the gas generating means with a small thickness stored in one combustion chamber, a value (Tl/Ts) of a thickness (Tl) of the gas generating means with a large thickness stored in another combustion chamber is adjusted in a range of between larger than 1 and not larger than 100. More concretely, in the case of defining first and second combustion chambers in the housing and respectively arranging the first gas generating means and the second gas generating means in the first combustion chamber and the second combustion chamber, a thickness of the first gas generating means to a thickness of the second gas generating means (mm) is adjusted to a range of between 0.1:10 and 10:0.1. In the porous cylindrical gas generating means, the thickness of the gas generating means can be measured by a method shown in an embodiment mentioned below.
When a plurality of combustion chambers are charged with the gas generating means having different surface areas per a unit weight from each other respectively, with respect to a surface area (Ss) of the gas generating means with a small surface area stored in one combustion chamber, a value (Sl/Ss) of a surface area (Sl) of the gas generating means with a large surface area stored in another combustion chamber can be suitably selected in a range of between larger than 1 and smaller than 50.
As mentioned above, in the gas generator storing the gas generating means being different in the shape and/or the amount in each of a plurality of combustion chambers, a ratio (TS1:TS2) of a total surface area (TS1) of the gas generating means stored in one combustion chamber to a total surface area (TS2) of the gas generating means stored in another combustion chamber can be adjusted in a range of between 1:50 and 50:1 in the case of a gas generator which is shorter in the axial direction than in the radial direction (for example, a gas generator for a driver side), and can be adjusted to a range of between 1:300 and 300:1 in the case of a gas generator which is longer in the axial direction than the radial direction (for example, a gas generator for passenger sides).
When changing an amount of the gas generating means in at each combustion chamber, a ratio (TW1:TW2) of a total weight (g) (TW1) of the gas generating means stored in one combustion chamber to a total weight (g) (TW2) of the gas generating means stored in another combustion chamber can be adjusted in a range of between 1:50 and 50:1 with a gas generator which is shorter in the axial direction than in the radial direction (for example, a gas generator for a driver side), and can be adjusted to a range of between 1:300 and 300:1 with a gas generator which is longer in the axial direction rather than the radial direction (for example, a gas generator for passenger sides).
In the gas generating means formed of a porous body, when using different one at each combustion chamber, it is possible to store a gas generating means formed in a porous cylindrical shape (for example, a seven-hole cylindrical body) in one combustion chamber and store a gas generating means formed in a single-hole cylindrical shape in another combustion chamber.
In the gas generator having the gas generating means stored in a plurality of combustion chambers, one of which is never ignited directly by combustion gas generated in the other combustion chambers, the gas generating means in each combustion chamber can be completely independently burnt in each combustion chamber. Accordingly, in this case, it is possible to independently ignite and burn the gas generating means stored in each combustion chamber in a more secure manner. As a result, even in the case of significantly staggering the activation timings of the ignition means provided in the respective combustion chambers, the flame of the gas generating means in one combustion chamber ignited by the firstly actuated ignition means does not burn the gas generating means in the rest of the combustion chambers, therefore, a stable operating output can be obtained.
Further, according to the present invention, in the gas generator mentioned above, there is provided a gas generator for an air bag, wherein two or more ignition means are disposed in the housing, and a combination of a gas discharge port formed in the housing and sealing means, such as a seal tape closing the gas discharge port, is characterized.
Namely, there is provided a gas generator for an air bag, having two or more ignition means to be ignited upon an impact, the gas generating means which is ignited and burnt by the ignition means and generate combustion gas for inflating an air bag, and the housing with a plurality of gas discharge ports formed thereon which forms an outer shell container, wherein the gas discharge ports are closed by sealing means for maintaining an internal pressure of the housing to a predetermined pressure, a rupturing pressure for breaking the sealing means is adjusted at multiple stages by controlling the gas discharge ports and/or the sealing means so as to suppress a difference of a maximum internal pressure of the housing at the time when each ignition means is activated, each of the two or more combustion chambers is charged with the gas generating means which is respectively different in at least one of a burning rate, shape, composition, composition ratio, and amount, and the gas generating means in each combustion chamber can be independently ignited and burnt at an optional timing.
The present invention provides a gas generator for an air bag comprising, in the housing having gas discharge ports, ignition means activated upon an impact and gas generating means ignited and burnt by the ignition means and generate combustion gas for inflating the air bag, characterized in that, in the housing, two combustion chambers for storing the gas generating means are provided concentrically so as to be adjacent to each other in the radial direction of the housing, and the communication hole which allows communication between the combustion chambers is provided, and the two combustion chambers are charged with the gas generating means respectively which are different from each other in at least one of a burning rate, shape, composition, composition ratio, and amount.
The present invention also provides a gas generator for an air bag comprising, in the housing having a gas discharge port, ignition means to be activated upon an impact and gas generating means ignited and burnt by the ignition means and generate a combustion gas for inflating the air bag, wherein, in the housing, the combustion chambers for storing the gas generating means are defined by partitioning into two or more chambers, and the gas generating means stored in each chamber is ignited and burnt independently by the igniter provided in each chamber and then generates a different amount of a gas per a unit time from each other in each chambers.
As mentioned above, when a plurality of combustion chambers are provided in the housing and charged with different gas generating means from each other, respectively, the gas generating means stored in each combustion chamber is independently ignited and burnt by the different ignition means at the same time or at intervals. By controlling an opening diameter (an opening area) of the gas discharge port and/or the thickness of the seal tape for closing the gas discharge port, the pressure (hereinafter, refer to as xe2x80x9ca combustion internal pressurexe2x80x9d) in the housing at the time when the gas generating means burns can be unified and the combustion performance can be stabilized. In this gas generator, each of two or more combustion chambers is charged with the gas generating means to provide different amounts of the generated gas at a unit time from each other respectively. The adjustment of the rupturing pressure mentioned above can be performed by arranging two or more kinds of opening diameters and/or opening areas of the gas discharge ports. Accordingly, with respect to two kinds of openings being next to each other with respect to diameters thereof among two or more kinds of gas discharge ports formed in the housing, it is preferable that a ratio between the large diameter gas discharge port and the small diameter gas discharge port is 4/1 to 1.1/1, and an opening area ratio is 97/3 to 3/97. Further, the adjustment of the rupturing pressure is performed by arranging two or more kinds of the thickness of the sealing means. Accordingly, with respect to two kinds of sealing means being next to each other with respect to the thickness thereof, among two or more kinds of the sealing means, it is preferable that a ratio between them is 1.1/1 and 12/1.
Further, in the gas generator, according to the present invention, where a plurality of combustion chambers are charged with the different gas generating means from each other, respectively, the gas discharge port may be arranged to have two or more opening diameters and/or opening areas, and the sealing means may be arranged to have two of more thickness. Further, it is preferable that the sealing means is a seal tape comprising a seal layer having a thickness of 20 to 200 xcexcm and a bonding layer or an adhesive layer having a thickness of 5 to 100 xcexcm. In the present invention, the seal tape means comprises a seal layer and a bonding layer or a adhesive layer. In the sealing means such as the seal tape, the rupturing pressure is adjusted by the size of the gas discharge port and/or the thickness thereof, but the maximum internal pressure in the housing at the time of combustion of the gas generating means (hereinafter, refer to as xe2x80x9ca combustion maximum internal pressurexe2x80x9d) and the combustion performance of the gas generating means are not adjusted.
Next, a description will be given of a gas generator including two igniters.
According to the present invention, as one solution, there is provided a gas generator for an air bag having, in the housing provided with a gas discharge port, ignition means actuated upon an impact, and gas generating means ignited and burnt by the ignition means and generate a combustion gas for inflating the air bag, wherein the ignition means includes two or more igniters activated upon an impact and the igniters are provided so as to be aligned to each other in an axial direction. Namely, the present invention provides a gas generator for an air bag comprising, in the housing provided with a gas discharge port, ignition means activated upon an impact, and gas generating means ignited and burnt by the ignition means and generate a combustion gas for inflating the air bag, wherein the ignition means has two igniters to be activated upon the impact and the igniters are provided integrally by resin.
Further, according to the present invention, there can be provided a gas generator for an air bag, wherein two or more igniters contained in the ignition means , as mentioned above, are installed and being fitted in a single initiator collar so as to be aligned to each other in the axial direction.
Still further, according to the present invention, there can be provided a gas generator for an air bag, wherein two or more igniters contained in the ignition means of the gas generator for the air bag, as mentioned above, are structured such that the igniters are integrated by a resin so as to be aligned to each other in the axial direction.
Furthermore, according to the present invention, there can be provided a gas generator for an air bag, wherein two or more igniters contained in the ignition means of the gas generator for the air bag, as mentioned above, are installed and being integrated by a resin in one initiator collar so as to be aligned to each other in the axial direction.
As mentioned above, in the air bag gas generator according to the present invention, since two or more igniters are provided so as to be aligned to each other in the axial direction, it is possible to draw out a lead wire for connection on the same plane in the same direction at a time of connecting the igniter to a control unit for the air bag apparatus.
Further, when two or more igniters are fitted into a single initiator collar and/or are integrated by a resin, a mounting operation to assemble the gas generator becomes easy.
Further, when two or more igniters are integrated by a resin in a single initiator collar, it is unnecessary to previously coincide an inner shape of the initiator collar with the outer shape of the igniter, and it is sufficient that an inner space of the initiator collar is at least larger than the size of the igniter. Further, when the igniters are integrated by the resin, a fixing member for the igniter is not required without regard to any mode of the gas generator.
According to the present invention, as an alternative solution, there is provided a gas generator for an air bag, having, in a housing provided with a gas discharge port, ignition means actuated upon an impact, and gas generating means ignited and burnt by the ignition means and generate combustion gas for inflating an air bag, wherein the ignition means includes two or more igniters activated upon an impact and the igniters are integrated by a resin.
According to the present invention, as a further alternative solution, there is provided a gas generator for an air bag having, in a housing provided with a gas discharge port, ignition means actuated upon an impact, and gas generating means ignited and burnt by the ignition means and generate a combustion gas for inflating an air bag, wherein the ignition means includes two or more igniters activated upon an impact, and the igniters are fitted into a single initiator collar.
As mentioned above, a gas generator having a simple structure and simple manufacturing steps can be provided by fixing two or more initiators by the igniter fixing member at the same time.
Further, according to the present invention, there can be provided a gas generator for an air bag in which two or more igniters contained in the ignition means of the above gas generator for the air bag are integrated by a resin in a single initiator collar.
Accordingly, when two or more igniters are fixed in a single initiator collar by the resin, it is unnecessary to previously coincide the inner shape of the initiator collar with the outer shape of the igniter, and it is sufficient that the inner space of the initiator collar is at least larger than the size of the igniter. Further, since the igniters are integrally fixed by the resin, a fixing member for the igniter is not required without regard to any mode of the gas generator.
In the gas generator according to the present invention, as the ignition means, an electric ignition type ignition means activated by an electric signal (or an activating signal) transmitted from an impact sensor or the like that detects an impact. The electric ignition type ignition means comprises an igniter activated on the basis of the electric signal transmitted from the electric type sensor which detects the impact exclusively by means of the electric mechanism such as a semiconductor type acceleration sensor, and a transfer charge ignited and burnt on activation of the igniter.
In the gas generator for the air bag according to the present invention, the elements other than the above solutions are not particularly limited, the same elements as those of a known gas generator for an air bag can be adopted, and any modification generally performed by those skilled in the art to the elements can be included.
Accordingly, the gas generator for the air bag according to the present invention can be structured to comprise two or more ignition means and two or more gas generating means (two or more combustion chambers and gas generating agents) which are independently ignited and burnt by the respective ignition means to generate a combustion gas for inflating the air bag.
Next, a description will be given of a gas generator including a combustion chamber and ignition means in an inner cylindrical member.
The gas generator for the air bag according to the present invention is a gas generator in which two combustion chambers are provided in the housing, and is characterized by an arrangement structure of two combustion chambers. It is possible to independently ignite and burn the gas generating means stored in the respective combustion chambers by different ignition means.
Namely, according to the present invention, there is provided a gas generator for an air bag, having, in a housing provided with a gas discharge port, ignition means actuated upon an impact, and gas generating means ignited and burnt by the ignition means and generate a combustion gas for inflating the air bag, wherein two combustion chambers storing the gas generating means are provided in the housing, a communicating hole which allows communication between the combustion chambers is provided, one of the two combustion chambers is provided in a side of the upper space of an inner cylindrical member disposed in the housing, the ignition means is provided in a side of the lower space of the inner cylindrical member, and the upper space and the lower space are defined by a partition wall.
Further, according to the present invention, there is provided a gas generator for an air bag, having, in a housing provided with a gas discharge port, ignition means activated upon an impact, and gas generating means ignited and burnt by the ignition means and generate a combustion gas for inflating the air bag, wherein, in the housing, two combustion chambers storing the gas generating means are concentrically provided so as to be adjacent to each other in the radial direction of the housing, the communicating hole which allows communication between the combustion chambers is provided, an inner combustion chamber of the two combustion chambers is provided in a side of the upper space of an inner cylindrical member disposed in the housing, the ignition means is provided in a side of the lower space of the inner cylindrical member, and the upper space and the lower space are defined by a partition wall.
Further, according to the present invention, there is provided a gas generator for an air bag having ignition means activated upon an impact, and gas generating means ignited and burnt by the ignition means and generate a combustion gas for inflating the air bag in a housing formed into a cylindrical shape having an axial core length longer than an outermost diameter, with a plurality of gas discharge ports on the peripheral wall thereof, wherein, in the housing, two combustion chambers storing the gas generating means are concentrically provided so as to be adjacent to each other in the axial direction and/or the radial direction of the housing, the communicating hole which allows communication between the combustion chambers is provided, an inner combustion chamber of the two combustion chambers is provided in a side of the upper space of an inner cylindrical member disposed in the housing, the ignition means is provided in a side of the lower space of the inner cylindrical member, and the upper space and the lower space are defined by a partition wall.
As mentioned above, the inner structure of the gas generator can be made simpler by arranging the inner combustion chamber and the ignition means in upper and lower portions in the axial direction in the space formed by the defining member.
Further, as mentioned above, by concentrically arranging the two combustion chambers in the housing, it is possible to make an inner structure of the gas generator simple and independently burn the gas generating agents in the respective combustion chambers.
The gas generator for the air bag according to the present invention includes the gas generator having the above structure and characterized by the arranging structure of one combustion chamber and the ignition means and a method of fixing two or more ignition means.
That is, according to the present invention, in the above gas generator for the air bag, there can be provided a gas generator for an air bag, wherein ignition means comprises two or more igniters activated upon an impact, and each igniter is provided in an initiator collar and fixed by an igniter fixing member which covers the upper surface of the initiator collar. Further, there can be provided a gas generator for an air bag, wherein the two or more igniters are provided in a single initiator collar.
As mentioned above, by fixing two or more igniters using the igniter fixing member at once, the structure and the manufacture becomes simple.
Further, according to the present invention, in the above gas generator for the air bag, there can be provided a gas generator for an air bag, wherein one of the two combustion chambers is provided outside the inner cylindrical member disposed in the housing, an inner space of the inner cylindrical member is defined by the other combustion chamber and an ignition means accommodating chamber in which the ignition means including the igniters is stored, by a partitioned circular member and a seal cup member engaged with the partitioned circular member. Further, there can be provided a gas generator for an air bag, wherein the partitioned circular member is engaged with a stepped notch portion provided on an inner peripheral surface of the inner cylindrical member. Still further, there can be provided a gas generator for an air bag, wherein a peripheral edge of the seal cup member is bent, and the bent portion of the peripheral edge is fitted into a groove provided on the inner peripheral surface of the inner cylindrical member.
Further, according to the present invention, in the above gas generator for the air bag, there can be provided a gas generator for an air bag, wherein the igniter contained in the ignition means is supported by the igniter fixing member which covers the upper surface of the initiator collar and fixed to the initiator collar, the seal cup member has an igniter receiving port extending to the igniter fixing member, an O-ring is arranged in a space constituted by the igniter fixing member, the igniter receiving port and the igniter, and the O-ring seals between the igniter fixing member and the igniter receiving port, between the igniter fixing member and the igniter, and between the igniter receiving port and the igniter.
Further, according to the present invention, in the above gas generator for the air bag, there can be provided a gas generator for an air bag, wherein an O-ring is interposed between a bent portion of the peripheral edge in the seal cup portion and the inner wall surface of the inner cylindrical member to which the bent portion is fitted.
As mentioned above, by using the seal cup member having a specific structure, it is unnecessary to interpose the O-ring in the fitting portion of the seal cup and the inner cylindrical member, and therefore, the diameter of the gas generator can be smaller. Further, since it is possible to maintain the ignition means in an airtight manner, a combustion of the transfer charge is uniformly performed in response to the activation of the igniter, and the internal pressure is increased by the combustion of the transfer charge, thereby expanding in the radial direction to press the inner wall surface of the inner cylindrical member to which the bent portion of the seal cup member is fitted, so that an air-tightness is further improved and a combustion of the transfer charge can be also uniformly performed.
Further, as mentioned above, by commonly using the igniter fixing member and the seal cup member together with the O-ring, it is possible to completely separate two or more igniters form each other.
Next, a description will be given of the gas generator which transmits an electric signal by a lead wire.
According to the present invention, there is provided a gas generator for an air bag, having ignition means actuated upon an impact, and gas generating means ignited and burnt by the ignition means and generate a combustion gas for inflating an air bag in a housing provided with a gas discharge port, wherein two combustion chambers storing the gas generating means are provided in the housing, the communicating hole which allows communication between the combustion chambers is provided, the ignition means comprises two or more igniters activated by an electric signal, a lead wire for transmitting the electric signal is connected to each igniter, and the lead wire is drawn out in the same direction on the same plane.
As the ignition means, electric ignition type ignition means activated by an electric signal (or an activating signal) transmitted from an impact sensor or the like for detecting the impact is used in the gas generator according to the present invention. The electric ignition type ignition means comprises an igniter which is actuated on the basis of the electric signal transmitted from the electric type sensor which detects an impact by an exclusively electric mechanism such as a semiconductor type acceleration sensor, and a transfer charge ignited and burnt in response to an activation of the igniter.
Further, in two or more igniters, it is preferable that the lead wires for transmitting the electric signal are connected via connectors and the connectors are arranged in parallel on the same plane.
Further, in two or more igniters, it is preferable that the lead wires for transmitting the electric signal are connected via the connectors and the lead wires are drawn out by the connectors in the same direction perpendicular to the axial direction of the housing.
Further, two or more igniters are preferably provided in a single initiator collar and aligning in the axial direction in order to facilitate mounting them.
Further, it is preferable that two combustion chambers storing the gas generating means are concentrically provided so as to be adjacent to each other in the radial direction of the housing and a communicating hole, which allows communication between the combustion chambers, is provided.
Further, according to the present invention, there is provided a gas generator for an air bag, having ignition means activated upon an impact, and gas generating means ignited and burnt by the ignition means and generate a combustion gas for inflating an air bag in a housing with a gas discharge port, wherein two combustion chambers storing the gas generating means are provided in the housing, a communicating hole which allows communication between the combustion chambers is provided. The ignition means comprises two or more igniters activated by an electric signal, a lead wire for transmitting the electric signal is connected to each igniter. A lead wire extending from one of the igniters extends substantially on an imaginary plane perpendicular to an axial direction of the housing and a lead wire extending from another of the igniters also extends substantially on the same plane.
The lead wires preferably extend 90 degrees or less, and more preferably 50 or 45 degrees or less with respect to one another, but can also be paralledl or extend in an opposite direction (180 degrees or less).
Further, in the gas generator for the air bag as mentioned above, there can be provided a gas generator for an air bag having ignition means activated upon an impact, and gas generating means ignited and burnt by the ignition means and generate a combustion gas, for inflating an air bag, in a housing provided with a plurality of gas discharge ports on a peripheral wall thereof and formed into a cylindrical shape having an axial core length longer than an outermost diameter, wherein, in the housing, two combustion chambers storing the gas generating means are concentrically provided so as to be adjacent to each other in the axial direction and/or the radial direction of the housing, and a communicating hole, which allows communication between the combustion chambers, is provided.
According to the present invention, two or more lead wires can be drawn out on the same plane and in the same direction by improving the mounting structure of the lead wire connected to two or more igniters, and therefore, it is possible to make an assembling process of the air bag apparatus using the gas generator for the air bag easy and also make the structure of the apparatus simple.
Next, a description will be given of a gas generator having an automatic ignition material.
A gas generator for an air bag according to the present invention corresponds to a gas generator having two combustion chambers in a housing, which can completely burn gas generating means left after the actuation of the gas generator. Accordingly, no inconvenience is affected at a time of later process, disposal or the like.
That is, according to the present invention, there is provided a gas generator for an air bag having ignition means activated upon an impact, and gas generating means ignited and burnt by the ignition means and generate a combustion gas, for inflating an air bag, in a housing provided with a gas discharge port, wherein, in the housing, two or more combustion chambers storing the gas generating means are defined, a communicating hole which allows communication between the combustion chambers is provided, and an automatic ignition material (AIM) ignited and burnt due to a transmitted heat is stored in one of the combustion chambers. For example, if the gas generating means stored in a plurality of combustion chambers are burnt at different timing at each combustion chamber, the automatic ignition material (AIM) is preferably stored in the combustion chamber where the gas generating means to be burnt at a delayed timing is stored. In this case, the automatic ignition material (AIM) can be ignited and burnt due to the transmission of the heat generated by combustion of the previously burnt gas generating agent. It is preferable that this automatic ignition material ignites the gas generating agent which is to be burnt at 100 milliseconds or more after the ignition means for igniting the gas generating means to be previously burnt is activated. Further, the automatic ignition material can be arranged so as to be combined with the igniter contained in the ignition means for igniting and burning the gas generating means to be burnt at a delayed timing (or possibly left after the actuation of the gas generator).
The gas generator which burns the gas generating means at the different timing at each combustion chamber can be realized, for example, by constituting the ignition means so as to include the transfer charge to be ignited and burnt by the activation of the igniter, dividing the transfer charge for each igniter so as to be independently ignited and burnt at each igniter, and igniting and burning the gas generating means stored in a plurality of combustion chambers with the flame by the combustion of the transfer charge in the different sections.
For example, in the gas generator in which two combustion chambers for storing the gas generating means are provided in the housing, the first gas generating means to be firstly burnt and the second gas generating means to be burnt at a later timing are arranged in each combustion chamber, and the first ignition means for igniting the first gas generating means and the second ignition means for igniting the second gas generating means are further provided, the automatic ignition material (AIM) is provided in the igniter contained in the second combustion chamber or the second ignition means. As the automatic ignition material (AIM), a material, which is ignited and burnt due to a heat generated by the combustion of the first gas generating means transmitted along the housing, is used.
In the case of forming two combustion chambers storing the gas generating means in the housing, two combustion chambers can be concentrically provided so as to be adjacent to each other in the radial direction of the housing and further a communication hole, which allows communication between the combustion chambers in the housing, can be provided.
The automatic ignition material (AIM), which can be used in the present invention, adopts a material which can be ignited and burnt at least due to a combustion heat of the (prior burning) gas generating means transmitted from the housing or the like (that is, a transfer heat) . As such a material, there is, for example, a nitrocellulose.
However, these can, of course, vary on a kind of the used gas generating means, a heat transferring member which transmits the combustion heat (for example, the housing), a distance with respect to a portion where the firstly burning gas generating means is stored. Therefore, it is necessary to suitably select and adopt them according to the design.